1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor optical waveguide device and to a semiconductor optical waveguide device.
2. Description of the Related Art
U.S. Pat. No. 6,310,995 (Patent Literature 1) discloses a spot size converter.
Spot size converters have various structures. For example, a spot size converter described in Patent Literature 1 includes a plurality of optical waveguide structures that are stacked on a substrate. At the spot size converter, light propagating through one of the optical waveguide structure is transferred to another optical waveguide structure.
In the spot size converter described in Patent Literature 1, a stacked semiconductor layer for forming the optical waveguide structures is formed in a single step of epitaxial layer growth. A plurality of waveguide mesas is formed from the stacked semiconductor layer to obtain the corresponding optical waveguide structures. For example, the spot size converter includes a semiconductor optical waveguide having a large mode filed diameter to optically couple to a single-mode optical waveguide (for example, an optical fiber). In addition, the spot size converter also includes a single-mode semiconductor optical waveguide having a small mode field diameter in which light having a single mode propagates.